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39899 Balentine Drive, Suite 125 Phone: 510 651 5122 Newark, CA 94560 Fax: 510 651 5127URL: MST Use Case ExampleVersion 118 January 2011PurposeThis is a companion document to DisplayPort Standard Version 1.2 and provides tangible examples of how a topology consisting of MST DP devices is to be managed while DisplayPort Standard describes the overall framework.SummaryThis document is Version 1 of the MST DP Usage Example Document Series, and covers how an MST DP Source device and a device containing MST Branching Unit are to interact with each other to perform typical topology and payload bandwidth management functions. A topology consisting of an MST DP Source device, an MST Splitter Branch device, and two video stream sinks is covered in this document.Table of ContentsPreface (7)Acknowledgements (8)Revision History (9)References (10)1 Example MST Topology without Audio Stream Sink (11)1.1 Topology Change Sequences of This Document (14)1.2 Topology Discovery (14)1.2.1 Source Device Operation (14)1.2.2 Splitter Branch Device Operation (21)1.3 Reading and Writing DP Device Global Unique Identifier (GUID) (21)1.3.1 Source Device Operation (22)1.3.2 Splitter Branch Device Operation (24)1.4 Obtaining Display Capabilities (25)1.4.1 Source Device Operation (25)1.4.2 Splitter Branch Device Operation (30)1.5 Establishing a Virtual Channel from PC to Display 1 (31)1.5.1 Source Device Operation (31)1.5.2 Splitter Branch Device Operation (36)1.6 Establishing a Virtual Channel from PC to Display 2 (37)1.6.1 Source Device Operation (37)1.6.2 Splitter Branch Device Operation (41)1.7 Reallocating the Virtual Channel from PC to Display 1 (41)1.7.1 Source Device (41)1.7.2 Splitter Branch Device Operation (45)1.8 Deleting Virtual Channel from PC to Display 1 (45)1.8.1 Source Device (45)1.8.2 Splitter Branch Device Operation (47)1.9 Cloning the Virtual Channel from PC to Display 2 on Display 1 (47)1.9.1 Source Device Operation (47)1.9.2 Splitter Branch Device Operation (49)1.10 Deleting Cloned Virtual Channel from PC to Display 2 (49)1.10.1 Source Device Operation (49)1.10.2 Splitter Branch Device Operation (50)1.11 Handling Unexpected Changes in Available PBN (51)1.11.1 Splitter Branch Device Operation (51)1.11.2 Source Device Operation (52)1.12 Entering and Exiting Sleep Mode (53)1.12.1 Source Device Operation (53)1.12.2 Splitter Branch Device Operation (56)1.13 Connection Status Change of a Remote Device Due to Unplug or Power Off Event (57)1.13.1 Splitter Branch Device Operation (57)1.13.2 Source Device Operation (58)1.14 Connection Status Change of a Remote Device Due to Plug or Power On Event (59)1.14.1 Splitter Branch Device Operation (59)1.14.2 Source Device Operation (60)2 Example MST Topology with Audio (62)2.1 Topology Discovery (63)2.2 Establishing a Virtual Channel from PC to Display 1 with Audio (66)2.3 Establishing a Virtual Channel from PC to Display 2 with Audio (67)3 Native AUX Transactions for Sideband MSG Delivery (69)3.1 Sideband MSG From uPacket TX to uPacket RX (DOWN_REQ or UP_REP) (69)3.2 Sideband MSG From uPacket RX to uPacket TX (UP_REQ or DOWN_REP) (69)4 Appendix A: MST Source Device Acting as SST-mode-only Device (70)5 Appendix B: MST Source Device with Two DP Output Connectors (71)TablesTable 0-1: Main Contributors (8)Table 1-1: Reference Documents (10)Table 1-1: LINK_ADDRESS Message Transaction (17)Table 1-2: LINK_ADDRESS Message Transaction Sideband MSG (17)Table 1-3: LINK_ADDRESS Message Transaction Reply (17)Table 1-4: LINK_ADDRESS Message Transaction Reply First Sideband MSG (19)Table 1-5: LINK_ADDRESS Message Transaction Reply Second Sideband MSG (20)Table 1-6: Sideband MSG for the GUID REMOTE_DPCD_READ Message Transaction Request 22 Table 1-7: Sideband MSG for the GUID REMOTE_DPCD_READ Message Transaction Reply (22)Table 1-8: Sideband MSG for the GUID REMOTE_DPCD_WRITE Message Transaction Request23 Table 1-9: Sideband MSG for the GUID REMOTE_DPCD_Write Message Transaction Reply (24)Table 1-10: Sideband MSG for the REMOTE_DPCD_WRITE Message Transaction Request Setting the I2C Speed to 100K (25)Table 1-11: Sideband MSG for the REMOTE_DPCD_WRITE Message Transaction Reply (26)Table 1-12: Message Transaction Request for Reading 128-Byte EDID from a Remote Sink Device26 Table 1-13: Sideband MSG for REMOTE_I2C_READ Message Transaction Request (27)Table 1-14: First Sideband MSG Reply for REMOTE_I2C_READ Message Transaction (28)Table 1-15: Second Sideband MSG Reply for REMOTE_I2C_READ Message Transaction (28)Table 1-16: Third Sideband MSG Reply for REMOTE_I2C_READ Message Transaction (29)Table 1-17: Fourth Sideband MSG Reply for REMOTE_I2C_READ Message Transaction Reply . 29 Table 1-18: ENUM_PATH_RESOURCES Message Transaction Request Sideband MSG (31)Table 1-19: ENUM_PATH_RESOURCES Message Transaction Reply Sideband MSG (32)Table 1-20: Virtual Channel (VC) Payload ID Table (35)Table 1-21: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG (35)Table 1-22: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG (36)Table 1-23: ENUM_PATH_RESOURCES Message Transaction Request Sideband MSG (37)Table 1-24: ENUM_PATH_RESOURCES Message Transaction Reply Sideband MSG (38)Table 1-25: uPacket TX and RX VC Payload ID Table (39)Table 1-26: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG (40)Table 1-27: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG (40)Table 1-28: uPacket TX and RX VC Payload ID Table (42)Table 1-29: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG for Reallocating a Virtual Channel (44)Table 1-30: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG for Reallocatinga Virtual Channel (44)Table 1-31: Delete VC ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG .. 45 Table 1-32: Delete VC ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG (46)Table 1-33: uPacket TX and uPacket RX VC Payload ID Table (47)Table 1-34: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG for Cloning Example (48)Table 1-35: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG for Cloning Example (48)Table 1-36: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG for Deleting a Cloned Virtual Channel Example (49)Table 1-37: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG for Deleting a Cloned Virtual Channel Example (50)Table 1-38: RESOURCE_STATUS_NOTIFY Message Transaction Request Sideband MSG (51)Table 1-39: RESOURCE_STATUS_NOTIFY Message Transaction Reply Sideband MSG (52)Table 1-40: POWER_DOWN_PHY Message Transaction Request Sideband MSG (53)Table 1-41: POWER_DOWN_PHY Message Transaction Reply Sideband MSG (53)Table 1-42: CLEAR_PAYLOAD_ID_TABLE Message Transaction Request Sideband MSG (54)Table 1-43: CLEAR_PAYLOAD_ID_TABLE Message Transaction Reply Sideband MSG (55)Table 1-44: POWER_UP_PHY Message Transaction Request Sideband MSG (55)Table 1-45: POWER_UP_PHY Message Transaction Reply Sideband MSG (56)Table 1-46: Unplug CONNECTION_STATUS_NOTIFY Broadcast Message Transaction Request Sideband MSG (57)Table 1-47: Unplug CONNECTION_STATUS_NOTIFY Broadcast Message Transaction Reply Sideband MSG (58)Table 1-48: Plug CONNECTION_STATUS_NOTIFY Broadcast Message Transaction Request Sideband MSG (59)Table 1-49: Plug CONNECTION_STATUS_NOTIFY Broadcast Message Transaction Reply Sideband MSG (60)Table 2-1: Audio Video Support Requirements (63)Table 2-2: LINK_ADDRESS Message Transaction Reply First Sideband MSG (64)Table 2-3: LINK_ADDRESS Message Transaction Reply Second Sideband MSG (65)Table 2-4: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG with Audio (66)Table 2-5: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG (66)Table 2-6: ALLOCATE_PAYLOAD Message Transaction Request Sideband MSG with Audio (67)Table 2-7: ALLOCATE_PAYLOAD Message Transaction Reply Sideband MSG (68)FiguresFigure 1-1: Logical Topology Covered in this Document (11)Figure 1-2: Physical Topology of PC and Multi-stream Sink Monitor (12)Figure 1-3: Physical Topology of PC and Multi-stream Sink Monitor (13)Figure 1-4: Physical Topology with Separate PC, Branch Device and Single Stream DP Monitors .. 13 Figure 1-5: Determine Whether LINK_ADDRESS Message Transaction Should be Used (15)Figure 1-6: Virtual Channel Allocation Procedure Flowchart (34)Figure 2-1: Audio Example Topology (62)PrefaceIntellectual PropertyCopyright © 2011 Video Electronics Standards Association. All rights reserved.While every precaution has been taken in the preparation of this standard, the Video Electronics Standards Association and its contributors assume no responsibility for errors or omissions, and make no warranties, expressed or implied, of functionality or suitability for any purpose.TrademarksAll trademarks used within this document are the property of their respective owners. DMT, DP, DisplayPort, EDID, and VESA are trademarks of the Video Electronics Standards Association.HDCP is a trademark of Digital Content Protection, LLCI2C is a trademark of Philips.PatentsVESA draws attention to the fact that it is claimed that compliance with this Standard may involve the use of a patent or other intellectual property right (collectively, “IPR”). VESA takes no position concerning the evidence, validity, and scope of this IPR.THIS STANDARD IS BEING OFFERED WITHOUT ANY WARRANTY WHATSOEVER, AND IN PARTICULAR, ANY WARRANTY OF NON-INFRINGEMENT IS EXPRESSLY DISCLAIMED. ANY IMPLEMENTATION OF THIS STANDARD SHALL BE MADE ENTIRELY AT THE IMPLEMENTER’S OWN RISK, AND NEITHER VESA, NOR ANY OF ITS MEMBERS OR SUBMITTERS, SHALL HAVE ANY LIABILITY WHATSOEVER TO ANY IMPLEMENTER OR THIRD PARTY FOR ANY DAMAGES OF ANY NATURE WHATSOEVER DIRECTLY OR INDIRECTLY ARISING FROM THE IMPLEMENTATION OF THIS STANDARD.Support for this StandardClarifications and application notes to support this standard may be written. To obtain the latest standard and any support documentation, contact VESA.If you have a product, which incorporates DisplayPort, you should ask the company that manufactured your product for assistance. If you are a manufacturer, VESA can assist you with any clarification you may require. Submit all comments or reported errors in writing to VESA using one of the following methods.•Fax: 510 651 5127, direct this fax to Technical Support at VESA•e-mail: support@•Mail: Technical SupportVESA39899 Balentine Drive, Suite 125Newark, CA 94560AcknowledgementsThis document would not have been possible without the efforts of VESA’s DisplayPort Task Group. In particular, the following individuals and their companies contributed significant time and knowledge to this version of the document.Table 0-1: Main ContributorsName CompanyTony Cheng AMDSyed Hussain AMDGeorge Kyriazis AppleBob Ridenour AppleYoshinobu Banba EIZO NANAOGeorge Hayek IntelSrikanth Kambhatla IntelCameron Buschardth NVIDIADavid Steers NVIDIAKen Jaramillo NXP SemiconductorJohn Garrett STMicroelectronics EditorAlan Kobayashi STMicroelectronics Co-editorRevision HistoryJanuary 18, 2011Initial ReleaseReferencesTable 1-2: Reference DocumentsDocument Version / Revision Date VESA Policy 200 Intellectual Property Rights Version B February 2005 VESA DisplayPort Standard Version 1.2 January 2010VESA and Industry Standards and Guidelines for Computer Display MonitorVersion 1. Rev.12 November 2008 Timing (DMTVESA Enhanced Extended Display Identification Data Standard (E-EDID) Rel. A Version 1 February 20001 Example MST Topology without Audio Stream SinkThis document covers how an MST DP Source device and a device containing MST Branching Unit are to interact to perform typical topology and payload bandwidth management functions in the following logical topology.Figure 1-4: Physical Topology with Separate PC, Branch Device and Single Stream DPMonitors1.1 Topology Change Sequences of This DocumentThere are two ways an MST DP Source device can be notified of a topology change.By a Hot Plug/Unplug event indicating a connection or disconnection of an immediate downstream device to its uPacket TX port.By receipt of a CONNECTION_STATUS_NOTIFY message transaction indicating a connection or disconnection of a remote device.Note: Alternately, the Topology Manager in a Source device may choose to periodically poll theUP_REQ_RDY bit of the immediate downstream device to monitor the connection change event.In this document, topology discovery and ensuing operations upon a plugging of an immediatedownstream device (that is, the Splitter to which to stream sinks are already connected) to an MST DP Source device is covered first. Connection status change of a remote device is covered later in thisdocument.1.2 Topology DiscoveryThis example explains the sequence of events necessary to discover the connected stream sinks. It is assumed that both stream sinks are connected to the branching unit before the branching unit isconnected to the source device.1.2.1Source Device OperationWhen the Splitter is plugged to the MST DP Source device, the Source device is notified of a HotPlug event via the detection of a long (that is, longer than 2ms) HPD pulse. Topology Manager of the DP Source device will read certain DPCD locations of the Splitter to determine the newly connected device type so that it can update the topology map to its Stream Policy Maker.The DPCD locations to be read for topology discovery are DPCD_REV,DOWNSTREAMPORT_PRESENT and MSTM_CAP. The given DPCD locations are read todetermine what type of DP device was connected and whether the device is MST capable (and thus capable of handling message transactions using Sideband MSGs) as shown in the following diagram.With the logical topology used in this document, the immediate downstream device has an MSTBranching Unit. Once it is determined that the device has an MST Branching Unit, the TopologyManager of the MST Source device must use the LINK_ADDRESS Message transaction to discover the devices connected to the Branching Unit.Figure 1-5: Determine Whether LINK_ADDRESS Message Transaction Should be Used The MST DP Source device sets UP_REQ_EN bit and UPSTREAM_IS_SRC bit of the immediate downstream device to declare itself as an MST DP Source device before issuing theLINK_ADDRESS Message Transaction to the immediate downstream device. The MST DP Sourcedevice uses the information received from the LINK_ADDRESS Message transaction to determine whether other DP MST Branching units are connected. If other DPMST Branching units are discovered, the LINK_ADDRESS Message transaction is sent to each DP MST Branching unit to determine the device connected to it. This procedure continues until the Source device’s search goals are met (all sinks found, first sink found or some other goal).An example algorithm to find all connected sinks is given below.Procedure FindAccessibleDPDevices given RAD of MST DP Branch device Send LINK_ADDRESS Message to address of MST DP Branching UnitWait wait_time_out time period (4 sec.) or until LINK_ADDRESS Message reply if wait_time_out time period elapsed without LINK_ADDRESS Message reply exit procedure indicating failureendifif device GUID field is empty (zeros)Write a GUID into the deviceelseif device already in list of devices foundif duplicate GUID obtained by traversing a loopexit procedure indicating a loopelseThere are multiple paths to the same deviceexit procedureendifendifendifAdd device to list of devices foundfor each downstream port of the MST DP Branch deviceif MST Branching Unit connected to downstream portExecute FindAccessibleDPDevices with address of MST DP Branch device elseAdd device to list of stream sinks/SST DP devicesendifendforend procedureThe Message Transaction source device will wait for 4 seconds for a reply for all message transactions. This is the time period to wait for the entire message transaction reply to be received; in other words, the wait time period for the last Sideband MSG for the message transaction reply to be received by the message source device.Given two RADs for the same DP MST device (same GUID), the following procedure will determine whether the DP MST device is part of a loop or is accessible through multiple paths.Procedure IsDevicePartOfLoop given RAD1 and RAD2 to same DP MST device if RAD1 has fewer links than RAD2Set SmallerRAD to RAD1Set LargerRAD to RAD2elseSet SmallerRAD to RAD2Set LargerRAD to RAD1endifSet N to the number of links in SmallerRADif the first N links of SmallerRAD is the same as the N links of LargerRAD return trueendifreturn falseend procedureThe list of sinks and SST DP devices from the above procedure will contain the relative address for the two stream sinks in this examples topology. The LINK_ADDRESS Message Transaction request and reply for this example are shown below.Table 1-1: LINK_ADDRESS Message TransactionLINK_ADDRESS Message Transaction Request Field Name ValueZeroRequest_Identifier 0000 0001Table 1-2: LINK_ADDRESS Message Transaction Sideband MSG LINK_ADDRESS Message Transaction Sideband MSG Request Field Name ValueLink_Count_TotalLink_Count_RemainingNo RADBroadcast_MessagePath_MessageSideband_MSG_Body_Length Start_Of_Message_Transaction End_Of_Message_Transaction zeroMessage_Sequence_No Sideband_MSG_Header_CRC zeroRequest_IdentifierSideband_MSG_Data_CRC 0001 000000 0010 111011000 0001 1101 0101The following shows the above values grouped into bytes.10h 02h CBh 01h D5hThe following LINK_ADDRESS Message Transaction reply will be received for the physical topology consisting of a PC connected to a daisy chainable monitor with an attached SST DP Monitor.Table 1-3: LINK_ADDRESS Message Transaction ReplyLINK_ADDRESS Message Transaction Reply Field Name ValueReply_TypeRequest_IdentifierGlobal_Unique_Identifier (GUID) of the originating branch device zerosNumber_Of_PortsInput_Port[0]Peer_Device_Type[0]Port_Number[0]Messaging_Capability_Status[0] 0000 0001 0000 0001 0000 0010 0000 0011 0000 0100 0000 0101 0000 0110 0000 0111 0000 1000 0000 1001 0000 1010 0000 1011 0000 1100 0000 1101 0000 1110 0000 1111 0001 0000 0000 00111001 00001DisplayPort_Device_Plug_Status[0]zerosInput_Port[1]Peer_Device_Type[1]Port_Number[1]Messaging_Capability_Status[1]DisplayPort_Device_Plug_Status[1]Legacy_Device_Plug_Status[1]zerosDPCD_Revision[1]Peer_Global_Unique_Identifier[1]Number_SDP_Streams[1]Number_SDP_Stream_Sinks[1]Input_Port[2]Peer_Device_Type[2]Port_Number[2]Messaging_Capability_Status[2]DisplayPort_Device_Plug_Status[2]Legacy_Device_Plug_Status[2]zerosDPCD_Revision[2]Peer_Global_Unique_Identifier[2] (Same as branch unit since this is a logical port) Number_SDP_Streams[2]Number_SDP_Stream_Sinks[2] 100 0000 0011 000110 0000 0001 0010 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000011 100010 0000 0001 0010 0000 0001 0000 0010 0000 0011 0000 0100 0000 0101 0000 0110 0000 0111 0000 1000 0000 1001 0000 1010 0000 1011 0000 1100 0000 1101 0000 1110 0000 1111 0001 0000 0000 0000The following shows the above values grouped into bytes. 01h 01h 02h 03h 04h 05h 06h 07h 08h 09h0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 03h 90h C0h31h 40h 12h 00h 00h 00h 00h 00h 00h 00h00h 00h 00h 00h 00h 00h 00h 00h 00h 00h38h 40h 12h 01h 02h 03h 04h 05h 06h 07h08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 00hSince the above LINK_ADDRESS Message Transaction reply is greater than 44-bytes (48 bytes minus the size of the Sideband Header and Sideband Body CRC, 3 + 41), the reply must be divided into multiple Sideband Messages. The LINK_ADDRESS Message Transaction reply is split into two Sideband Messages between the DPCD_Version[2] and GUID[2]. With this split, the first Sideband Message is 47-bytes, and the second Sideband message is 21-bytes. The split can be performed at any point as long as the resultant Sideband messages are less than or equal to 48-bytes. In this case the split of the Message Transaction reply should not result in more than two Sideband messages. Table 1-4: LINK_ADDRESS Message Transaction Reply First Sideband MSGLINK_ADDRESS Message Transaction Reply Field Name ValueLink_Count_TotalLink_Count_RemainingNo RADBroadcast_MessagePath_MessageSideband_MSG_Body_LengthStart_Of_Message_TransactionEnd_Of_Message_TransactionzeroMessage_Sequence_NoSideband_MSG_Header_CRCReply_TypeRequest_IdentifierGlobal_Unique_Identifier (GUID) of the originating branch device zerosNumber_Of_PortsInput_Port[0]Peer_Device_Type[0]Port_Number[0]Messaging_Capability_Status[0]DisplayPort_Device_Plug_Status[0]zerosInput_Port[1]Peer_Device_Type[1] 0001 000010 1100 11001000 0001 0000 0001 0000 0010 0000 0011 0000 0100 0000 0101 0000 0110 0000 0111 0000 1000 0000 1001 0000 1010 0000 1011 0000 1100 0000 1101 0000 1110 0000 1111 0001 0000 0000 00111001 00001100 0000 0011Port_Number[1]Messaging_Capability_Status[1] DisplayPort_Device_Plug_Status[1] Legacy_Device_Plug_Status[1] zerosDPCD_Revision[1]Peer_Global_Unique_Identifier[1] Number_SDP_Streams[1] Number_SDP_Stream_Sinks[1] Input_Port[2]Peer_Device_Type[2]Port_Number[2]Messaging_Capability_Status[2] DisplayPort_Device_Plug_Status[2] Legacy_Device_Plug_Status[2] zerosDPCD_Revision[2]Sideband_MSG_Data_CRC 000110 0000 0001 0010 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000011 100010 0000 0001 0010 0010 1000The following shows the above values grouped into bytes.10h 2Ch 89h 01h 01h 02h 03h 04h 05h 06h07h 08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h03h 90h C0h 31h 40h 12h 00h 00h 00h 00h00h 00h 00h 00h 00h 00h 00h 00h 00h 00h00h 00h 00h 38h 40h 12h 28hTable 1-5: LINK_ADDRESS Message Transaction Reply Second Sideband MSG LINK_ADDRESS Message Transaction Reply Field Name ValueLink_Count_TotalLink_Count_RemainingNo RADBroadcast_MessagePath_MessageSideband_MSG_Body_LengthStart_Of_Message_TransactionEnd_Of_Message_TransactionzeroMessage_Sequence_NoSideband_MSG_Header_CRCPeer_Global_Unique_Identifier[2] (Same as branch unit since 0001 000001 0010 011111 0000 0001this is a logical port) Number_SDP_Streams[2]Number_SDP_Stream_Sinks[2]Sideband_MSG_Data_CRC 0000 0010 0000 0011 0000 0100 0000 0101 0000 0110 0000 0111 0000 1000 0000 1001 0000 1010 0000 1011 0000 1100 0000 1101 0000 1110 0000 1111 0001 0000 0000 0000 0011 1011The following shows the above values grouped into bytes.10h 12h 4Fh 01h 02h 03h 04h 05h 06h 07h08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 00h3Bh1.2.2Splitter Branch Device OperationWhen a Splitter Branch device completes initializing and is ready to handle AUX request transactions from its upstream device, the Splitter Branch device will assert HPD on its upstream physical port.Part of the initialization sequence is setting the MSTM_CAP DPCD location MST_CAP bit to 1. The Splitter Branch device will begin monitoring its downstream ports for device connections. When the Splitter Branch device detects devices connected to its downstream ports, its Topology Assistant has the option of reading the device information from the connected DP device for later reporting when a LINK_ADDRESS Message Transaction is received from the Topology Manager in the Sourcedevice; alternately, it may do nothing, just waiting for the LINK_ADDRESS Message Transactionbefore reading the device information of the connected DP device. Table 2-93 of the VESADisplayPort Standard Ver.1.2 describes what information needs to be obtained to determine thevalues for the Peer_Device_Type and Messaging_Capability_Status fields of the LINK_ADDRESS Message Transaction reply.The Splitter Branch device will monitor the MSTM_CTRL DPCD location UP_REQ_EN bit. When the UP_REQ_EN bit is set to 1 by the upstream device(s), it will set the UP_REQ_EN bit of thedownstream devices to 1 as long as those devices are MST devices (indicated by the MST_CAP bit equal to 1).Note: When the UP_REQ_EN bit is cleared to (or remains) 0 on the upstream port by the upstream device, the Splitter Branch device will clear the UP_REQ_EN bit of the downstream devices to 0 and operate as an SST Branch device (either an output switch or a replicater) as described in Section 3.”.1.3 Reading and Writing DP Device Global Unique Identifier (GUID)In this example the SST DP Sink device Display 1 supports HBR2. Therefore, Display 1 needs to have DPCD revision number 1.2. Because it has DPCD revision number 1.2, Display 1 must have a GUID field. Assuming Display 1 doesn’t contain a USB device, the GUID field can be set to zero as power-on reset default value. If the GUID field is set to zero, the GUID field must be writable using Native AUX CH transactions. This example provides the Message transactions required to read andsubsequently write the GUID field assuming the GUID field is set to zero.1.3.1Source Device OperationFrom the LINK_ADDRESS Message Transaction reply received from the last branch device, the MST DP Source device knows the DPCD version number supported by the SST DP Sink devices.For Display 1 the DPCD revision number supported is 1.2 indicating it supports a GUID field. The MST DP Source device sends a REMOTE_DPCD_READ Message Transaction request to the last branch device to read the GUID field of Display 1. The Sideband MSG containing theREMOTE_DPCD_READ Message Transaction request is shown in the following table.Table 1-6: Sideband MSG for the GUID REMOTE_DPCD_READ Message TransactionRequestREMOTE_DPCD_READ Message Transaction Request Sideband MSG Field Name ValueLink_Count_TotalLink_Count_RemainingNo RADBroadcast_MessagePath_MessageSideband_MSG_Body_Length Start_Of_Message_Transaction End_Of_Message_Transaction zeroMessage_Sequence_No Sideband_MSG_Header_CRC zeroRequest_IdentifierPort_NumberDPCD_AddressNumber_Of_Bytes_To_Read Sideband_MSG_Data_CRC 0001 000000 0110 111100010 0000 0001 0000 0000 0000 0011 0000 0001 0000 1110 1010The following shows the above values grouped into bytes.10h 06h CCh 20h 10h 00h 30h 10h EAhThe GUID field read will be zero. The reply to the above Message transaction request is shown in the table below.Table 1-7: Sideband MSG for the GUID REMOTE_DPCD_READ Message Transaction Reply REMOTE_DPCD_READ Message Transaction Reply Sideband MSG Field Name ValueLink_Count_TotalLink_Count_RemainingNo RADBroadcast_MessagePath_MessageSideband_MSG_Body_Length Start_Of_Message_Transaction End_Of_Message_Transaction zeroMessage_Sequence_No Sideband_MSG_Header_CRC Reply_TypeRequest_IdentifierzerosPort_NumberNumber_Of_Bytes_Read Data_Read[0] GUIDData_Read[1] 0001 000001 0100 111001010 0000 0000 0001 0001 0000 0000 0000 0000 0000。

DS9705B-03 April 201180m Ω, 1A Power MultiplexerGeneral DescriptionThe RT9705B is a dual input single output power multiplexer specifically designed to provide seamless voltage transition between two independent power suppliers. Equipped with two low R DS(ON) N-Channel MOSFETs driven by internal charge pump circuitry, the RT9705B is able to deliver 1A output current with only 80mV voltage drop. Manual or auto switching mode is easily selected by two digital inputs D1 and D0. When both D0and D1 are selected high, the RT9705B enters shutdown mode and consumes minimum power making it ideal suitable for battery powered equipments. A STAT pin with open drain output is provided to indicate the switch status.A user-programmable up to 1.25A current limit function is available for maximum safety in various applications.The RT9705B provides comprehensive protection functions,including adjustable current limit, over temperature protection, soft start function for minimum inrush current,cross-conduction protection, and reverse conduction protection. These features greatly simplify power multiplexer design. The RT9705B is available in TSSOP-8package requiring minimum board area and smallest components.Featuresz Adjustable Current Limiting up to 1.25Az Built-In (Typically 80m Ω) N-Channel MOSFET zReverse Current Flow Blocking (no body diode) i.e.Output Can Be Forced Higher than Input (Off-State)zLow Supply Current :`55μA Typical at Switch on State`Less than 0.5μA Typical at Switch Off State z Guaranteed 1A Continuous Load Current z Wide Input Voltage Ranges : 2.8V to 5.5V z Open-Drain STAT Outputz Hot Plug-In Application (Soft-Start)z Thermal Shutdown Protectionz Smallest TSSOP-8 Package Minimizes Board Space zRoHS Compliant and 100% Lead (Pb)-FreeApplicationsz LCD Monitor, LCD-TVz Information Appliance and Set-Top Box z Battery-Powered Equipment z ACPI Power Distributionz Motherboard & Notebook PCs z Mini PCI & PCI-Express Cards zPCMCIA & New CardsPin Configurations(TOP VIEW)TSSOP-8Ordering InformationSTAT D0D1ILIMGNDVIN2VOUT VIN1Note :Richtek products are :` RoHS compliant and compatible with the current require-ments of IPC/JEDEC J-STD-020.` Suitable for use in SnPb or Pb-free soldering processes.Marking InformationFor marking information, contact our sales representative directly or through a Richtek distributor located in yourarea.Package Type C : TSSOP-8RT9705BLead Plating System P : Pb FreeG : Green (Halogen Free and Pb Free)Typical Application CircuitTable 1. Truth TableNotes for Table 1.1. X : Don ’t care2. Hi-Z: High impedance node3. D0 and D1 cannot be floating which will lead to an unknown state.4. An internal MOSFET with 2k Ω R DS(ON) turns on and softly discharges the output voltage when D0 = D1 = 1.V V OUTDS9705B-03 April 2011Test CircuitsTest Circuit 1Test Circuit 2Test Circuit 3Test Circuit 4f = 28Hzf = 580Hz5VV OUTFunction Block DiagramTiming DiagramV 5VQ1 EnabledQ2 EnabledV 3.3VV OUT (a)(b)(c)DS9705B-03 April 2011Electrical Characteristicsz Input Voltage, VIN1 & VIN2-----------------------------------------------------------------------------------------−0.3V to 6.0V z Logic Inputs Voltage, D0 &D1--------------------------------------------------------------------------------------−0.3V to 6.0V z Output Voltage, VOUT , STAT & ILIM -----------------------------------------------------------------------------−0.3V to 6.0V zPower Dissipation, P D @ T A = 25°CTSSOP-8----------------------------------------------------------------------------------------------------------------0.43W zPackage Thermal Resistance (Note 2)TSSOP-8, θJA ----------------------------------------------------------------------------------------------------------230°C/W z Junction T emperature -------------------------------------------------------------------------------------------------125°C z Lead Temperature (Soldering, 10 sec.)---------------------------------------------------------------------------260°Cz Storage T emperature Range ----------------------------------------------------------------------------------------−65°C to 150°C zESD Susceptibility (Note 3)HBM (Human Body Mode)------------------------------------------------------------------------------------------2kV MM (Machine Mode)--------------------------------------------------------------------------------------------------200VAbsolute Maximum Ratings (Note 1)To be continuedRecommended Operating Conditions (Note 4)zInput VoltageV IN1 ( if V IN2 2.8V)--------------------------------------------------------------------------------------------------2.3V to 5.5V V IN1 ( if V IN2 < 2.8V)--------------------------------------------------------------------------------------------------2.8V to 5.5V V IN2 ( if V IN1 2.8V)--------------------------------------------------------------------------------------------------2.3V to 5.5V V IN2 ( if V IN1 < 2.8V)--------------------------------------------------------------------------------------------------2.8V to 5.5V z Logic Inputs Voltage (D0 &D1)-------------------------------------------------------------------------------------0V to 5.5V z Junction T emperature Range ----------------------------------------------------------------------------------------−40°C to 125°C z Ambient T emperature Range ----------------------------------------------------------------------------------------−40°C to 85°C≥≥To be continuedDS9705B-03 April 2011Note 1. Stresses listed as the above “Absolute MaximumRatings ” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied.Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability.Note 2. θJA is measured in the natural convection atT A = 25°C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard.Note 3. Devices are ESD sensitive. Handling precautionrecommended.Note 4. The device is not guaranteed to function outside itsoperating conditions.Note 5. Performance at −5°C ≤ T A ≤ 85°C is assured bydesign.Note 6. Not tested for production.Note 7. The UVLO is without latch. In V IN falling dege, theoutput voltage will depend on I OUT and C OUT . Please see below curve as reference.V IN2 = 2.2V, C OUT = 10uF, R L = 180ΩV OUT Response vs. UVLOTime (1ms/Div)V OUT(1V/Div)V IN1(1V/Div)R DS(ON) vs. Temperature5060708090100110-50-25255075100125Temperature (°C)R D S (O N ) (m Ω)Typical Operating CharacteristicsR e f e r t o T e s t C i r c u i t s 2Output Turn-On ResponseTime (1ms/Div)D0D1V OUT(2V/Div)(2V/Div)(2V/Div)D0 = 1 0, D1 = 1, V IN1 = 5V, V IN2 = 3.3V↔Output Switchover ResponseTime (1ms/Div)D1D0V OUT(2V/Div)(2V/Div)(2V/Div)D0 = 0, D1 = 1 0V IN1 = 5V, V IN2 = 3.3V↔R e f e r t o T e s t C i r c u i t s 1Current Limit vs. Junction Temperature00.20.40.60.811.21.41.61.82-50-25255075100125Junction Temperature C u rr e n t L i m i t (A )(°C)R DS(ON) vs. Input Voltage606570758085902.53 3.54 4.55 5.56Input Voltage (V)R D S (O N ) (m Ω)Quiescent Current vs. Input Voltage303540455055602.53 3.54 4.55 5.56Input Voltage (V)Q u i e s c e n t C u r r en t (u A )DS9705B-03 April 2011Output Switchover Voltage DroopTime (50μs/Div)D1V OUT(2V/Div)(2V/Div), C OUT = 1uF (2V/Div), C OUT = openD0 = 0, D1 = 1 0, V IN1 = V IN2 = 5V, RL = 50Ω↔R e f e r t o T e s t C i r c u i t s 3Auto Switchover Voltage DroopTime (250μs/Div)(2V/Div)(2V/Div)V OUTV IN1D0 = 1, D1 = 0, V IN1 = 5 0V, V IN2 = 3.3V↔R e f e r t o T e s t C i r c u i t s 4Output Switchover Voltage Droop vs. C OUT00.20.40.60.811.21.41.60.1110100C OUT (uF)O u t p u t S w i t c h o v e r V o l t a g e D r o o p (V )Application InformationThe RT9705B is dual input single output power multiplexer specifically designed to provide seamless voltage transition between two independent power suppliers. Equipped with two low R DS(ON) N-Channel MOSFETs driven by internal charge pump circuitry, the RT9705B is able to deliver 1A output current with only 80mV voltage drop. The RT9705B provides comprehensive protection functions, including adjustable current limit, over temperature protection, soft start function for minimum inrush current, cross-conduction protection, and reverse conduction protection. These features greatly simplify power multiplexer design.Manual Switching ModeThe RT9705B provides two logic input D0 and D1 for switch selection as shown in Table 1. The RT9705B selects the manual-switching mode when the D0 is pulled low. In this mode V OUT connects to V IN1 if D1 pulled high, otherwise V OUT connects to V IN2.Auto Switching ModeRT9705B selects the auto-switching mode when the D0 is pulled high and D1 is pulled low. In this mode V OUT connects to the higher of V IN1 and V IN2.Shutdown ModeWhen both D0 and D1 are selected high, the RT9705B enters shutdown mode and consumes minimum power. An internal MOSFET with 2kΩ R DS(ON) turns on and softly discharges the output voltage in the shutdown mode. Since no body diode exists between V INX and V OUT, output voltage is allowed to be high than the input voltages in the shutdown mode.Switch Status IndicationA STAT pin with open drain output is provided to indicate the switch status. STAT pin outputs high impedance if V IN2 is active, otherwise STAT pin outputs low.Current LimitingThe current limit circuitry prevents damage to the MOSFET switch and external load. A resistor R ILIM from ILIM to GND sets the current limit to 500/R ILIM and the adjustable current limiting up to 1.25 A. A setting resistor R ILIM equal to zero is not recommended as that disables current limiting.Thermal ConsiderationsThermal protection limits power dissipation in RT9705B. When the operation junction temperature exceeds 135°C, the OTP circuit starts the thermal shutdown function and turns the pass element off. The pass element turn on again after the junction temperature cools by 10°C.For continuous operation, do not exceed absolute maximum operation junction temperature 125°C. The power dissipation definition in device is :P D = (V IN-V OUT) x I OUT + V IN x I QThe maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula :P D(MAX) = ( T J(MAX) - T A ) / θJAwhere T J(MAX) is the maximum operation junction temperature 125°C, T A is the ambient temperature and the θJA is the junction to ambient thermal resistance.For recommended operating conditions specification of RT9705B, where T J(MAX) is the maximum junction temperature of the die (125°C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (θJA is layout dependent) for TSSOP-8 package is 230°C/W on standard JEDEC 51-3 thermal test board. The maximum power dissipation at T A = 25°C can be calculated by following formula :P D(MAX) = (125°C -25°C) / 230°C/W = 430 mW (TSSOP-8)RT9705B11DS9705B-03 April 2011Layout ConsiderationIn order to meet the voltage drop, droop, and EMI requirements, careful PCB layout is necessary. The following guidelines must be considered :zKeep all main current traces as short and wide as possible.z Place a ground plane under all circuitry to lower both resistance and inductance and improve DC and transient performance (Use a separate ground and power plans if possible).zLocate the ceramic input capacitors as close as possible to the VIN and GND pins of the device.Figure 1. Top Layer Figure 2. Bottom Layer12DS9705B-03 April Richtek Technology CorporationHeadquarter5F, No. 20, Taiyuen Street, Chupei CityHsinchu, Taiwan, R.O.C.Tel: (8863)5526789 Fax: (8863)5526611Richtek Technology Corporation Taipei Office (Marketing)5F, No. 95, Minchiuan Road, Hsintien City Taipei County, Taiwan, R.O.C.Tel: (8862)86672399 Fax: (8862)86672377Email:*********************Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design,specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.8-Lead TSSOP Plastic Package。